SNO SNO Steve Biller Oxford University total SSM
SNO + SNO+ Steve Biller, Oxford University
total SSM (unconstrained CC spectrum) June 2001 (indirect) April 2002 (direct) Sept 2003 (salt - unconstrained) May 2008 (indep. NCD measurement)
Reduce Systematic Uncertainties Old (D 2 O, salt) Energy Scale: 1. 2% Resn: 4. 5, 3. 4% New β 14 Electron: 0. 85% 0. 24 % R 3 Fid Vol: 3% < 1% Ang Resn: 16% 11% Ncap: >2% 1. 2% cos θsun < 0. 5% < 2% “Contamination” Normalization (neutrons, others) PMT - distributions
Ideal (and correct!) Way To Propagate Uncertainties: “Float” uncertainties as variable parameters in Likelihood fit, appropriately constrained by any independently determined bounds. In 4 dimensions with >50 parameters and limited MC statistics for PDFs ? ! Two Approaches:
1) Float Dominant Systematics via a “Brute Force” Iterative Scan of the Likelihood Space (shift & smear the rest)
Kernel 2) Colonel Estimated PDFs
Approach is very (prohibitively) CPU intensive … so don’t use CPUs!!
8 B Flux Result
8 B Flux Result NC = 5. 140 +4. 0 -3. 8 % (x 106 cm-2 s-1)
8 B Flux Result NC = 5. 140 +4. 0 -3. 8 % (x 106 cm-2 s-1) J. N. Bahcall, A. M. Serenelli, and S. Basu, Astro. Phys. J. 621, L 85 (2005)
CC Recoil-Electron Spectrum
New Previous Oscillation Analysis (LETA) LETA 2010: SNOpaper PRL 2008: LETA joint-phase fit Phase I + Phase IIIII + Phase III
Solar + Kam. LAND 3 -flavor Overlay LETA paper 2010: LETA joint-phase fit + Phase III + all solar expts + Kam. LAND 3 -flavor analysis: Best-fit: sin 2 13 = 0. 02 +0. 02 -0. 016 sin 2 13 < 0. 057 (95% C. L. ) 3 model
Last bit of SNO: 3 -Phase Analysis
Physics with Liquid Scintillator o Neutrinoless double beta decay various isotopes possible o Low energy solar neutrinos pep, CNO, 8 B and potentially 7 Be & pp o Geo-neutrinos unmatched o 240 km baseline reactor neutrino oscillation m 2 resolution comparable to Kam. LAND o Supernova neutrinos major player o “Invisible” modes of nucleon decay unique sensitivity with initial water data
Queen’s University Laurentian University of Alberta TRIUMF SNOLAB University of Pennsylvania University of Washington Black Hills State University Armstrong Atlantic University of North Carolina Brookhaven National Lab Oxford University Sussex University Leeds University Liverpool University Sheffield University QMUL LIP Lisbon TU Dresden
Now part of larger SNOLAB major underground science facility. Nigel Smith is now the director.
SNO+ AV Hold Down Existing AV Support Ropes
SNO+ AV Hold Down Existing AV Support Ropes AV Hold Down Ropes
• Electronics refurbishment • Improved cover-gas system • New glovebox • Repair of liner • Re-sanding of acrylic vessel • Overhaul of software design • New calibration systems • New purification systems • Replacement of pipes • • •
Acrylic Vessel Cleaning and Sanding Platforms
Neutrinoless Double -Decay
Light Output and Concentration “extremes”
“Ideal” Statistical Optimisation
How do you firmly establish whether a possible signal is actually 0 2 ? Two methods: 1) Redundancy 2) Redundancy Different isotopes with signals predicted at different energies, with different backgrounds, and different signal rates that scale correctly with the corresponding matrix elements.
350 Klapdor-Kleingrothaus 300 m (me. V) 250 200 150 100 50 Inverted Heirarchy 0 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
350 Klapdor-Kleingrothaus 300 SUPER NEMO (demonstrator) GERDA I m (me. V) 250 EXO 200 150 II CUORE GERDA KAMLANDSNO+ CUORE 100 50 SUPER NEMO SNO+ II ? Inverted Heirarchy 0 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
Towards SNO++ 150 Nd enrichment Nanoparticles Other Isotopes
Low Energy Solar Neutrinos
Solar Neutrinos Detail MSW transition (neutrino-matter couplings), Solar Composition Problem, etc. p-p Solar Fusion Chain p + p 2 H + e + + e 2 H 3 He + p 3 He + + 3 He 4 He + 2 p 3 He p + e − + p 2 H + e 3 He + p 4 He + e+ + e CNO Cycle + 4 He 7 Be + 12 C + p → 13 N + 13 N → 13 C + e+ + 7 Be + e− 7 Li + + e 7 Be + p 8 B + 13 C + p → 14 N + p → 15 O + 7 Li +p + 8 B 2 + e+ + e e 15 N + p → 12 C + 15 O → 15 N + e+ + e
SNOLAB depth of 6000 mwe gives a muon flux 800 times less than Kam. LAND and virtually eliminates background from 11 C, making SNO+ uniquely sensitive for a precision measurement. pep signal ( 4000 events/yr) After 3 years: ~5% uncertainty CNO Signal After 3 years: ~8% uncertainty 210 Bi background Can be inferred from 210 Po peak 40 K background Can be constrained by peak 3600 pep events/(kton·year), for electron recoils >0. 8 Me. V 210 Bi (U), 40 K are most important for solar studies. Borexino has demonstrated similar levels of backgrounds.
Geo-Neutrinos
Geo-Neutrino Signal antineutrino events e + p → e+ + n: • Kam. LAND: 33 events per year (1000 tons CH 2) / 142 events reactor • SNO+: 44 events per year (1000 tons CH 2) / 38 events reactor Kam. LAND SNO+ geo-neutrinos and reactor background Kam. LAND geo-neutrino detection…July 28, 2005 in Nature
Reactor Neutrinos
Reactors Contribution to the Spectrum • Bruce reactor will contribute mainly to the central peak. • We can take advantage from any “shut-off” period L/E Analysis Main Reactors (distances smaller than 700 km to the detector) Reactor d (km) Th. Power (GW) Bruce 281 10, 32 Pickering 330 6, 192 Darlington 340 10, 572 R. E. Ginna 455 1, 41 James A. Fitzpatrick 488 2, 34 Nine Mile Point 488 5, 07 Perry 530 3, 1615 Enrico Fermi 559 3, 255 Kewaunee 568 1, 509 Davis-Besse 588 2, 531 Point Beach 589 2, 91 Palisades 617 2, 34 Gentily 648 1, 914 Beaver Valley 657 4, 929 Donald C. Cook 685 3, 06
Nucleon Decay
“Invisible” Modes of Nucleon Decay modes where negligible visible energy from by-products is deposited in the detector For example: Violates (B-L) (interesting for matter/antimatter asymmetry) Models can be constructed where this is primary mode {Mohapatra & Perez-Lorenzana, Phys Rev D 67, 075015 (2003)} How? 16 O ~6 Me. V γ Order of magnitude improvement on current bound may be possible with just a few months of data !!
First Data in 2012 Rough Order or Running: Pure Scintillator ~ few years detailed solar study Follow-on Phase ~ ? Phase II ? Other ? live for supernova running Nd-loaded Scintillator ~ few years Phase I reactor neutrinos Pure Scintillator ~ several months initial solar study geo-neutrinos H 2 O ~ couple months nucleon decay
CC Recoil-Electron Spectrum Flat: 2 = 21. 52 / 15 d. o. f. LMA: 2 = 22. 56 / 15 d. o. f. Previous global best-fit LMA point: tan 2 12 = 0. 468, m 2 = 7. 59 x 10 -5 e. V 2
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